This invention relates to alloys and has particular reference to alloys of titanium and nickel intended for use as anodes in electrowinning cells and has further reference to methods of operating electrowinning cells incorporating such anodes.
The present invention is concerned with the provision of alloys of titanium and nickel which are suitable as anodes for electrometallurgical applications. In the electrowinning of metals a solution, normally an aqueous solution containing ions of the metal to be won, is treated in an electrowinning bath or vat to extract metal from the solution. Alternating anodes and cathodes are positioned in the solution in the bath and an electrical current is passed between them. The metal is normally deposited onto the cathode and oxygen is evolved at the anode. The anode has to be able to withstand the aggressive conditions resulting from the evolution of oxygen at the surface of the material. There have been many materials used in practice over the past one hundred years. The principal materials for the anodes have comprised lead or lead alloys such as lead-silver or lead-calcium and complex silicides such as Luilu, which is a cobalt silicide, or Chilex, which is a copper silicide.
With the development of precious metal-containing anodes for the electrochemical industry attempts have been made to use anodes formed of titanium having a precious metal or precious metal oxide coating. To date these anodes have not been of any significant commercial use, the main reason being that they have too high a capital cost in relation to their life. It has been proposed to use a semiconsumable material such as is described in U.S. Pat. No. 3,957,600. That U.S. patent describes the use of alloys of a film-forming metal together with one or more elements of Atomic Nos. 23 to 29 as anodes in the electrowinning of metal from an aqueous solution. The present invention is concerned with the use of materials of the type generally described in U.S. Pat. No. 3,957,600. The present invention is a selection of certain limited ranges of materials which have been found to have unique mechanical strength and low wear rates.